A class-wide study of LDPE-oxidase enzymes to delineate design rules for enzymatic LDPE oxidation

Project Description

Plastics production has been exponentially rising since its onset in the 1950s and is predicted to continue to increase. This production increase is coupled with a rise in waste generation, leaving nearly 400 million tons of untouched carbon that can be used as a feedstock for (bio)manufacturing to offset crude oil usage. Widely used mechanical and chemical recycling approaches are economically limited due to loss of mechanical integrity and high process energy requirements, respectively. Biological upcycling offers a sustainable alternative by operating near ambient conditions and allowing for product selectivity of upcycled products. Though biological approaches have proven effective for plastics such as poly(ethylene terephthalate) (PET), there is a lack of enzymes available for conversion of polyethylene (PE), the most abundant global waste plastic. This lack of PE deconstructing enzymes is driven by an absence of chemical functionality on the polymer backbone that limits bioavailability. We recently discovered a class of enzymes that oxidize low-density PE (LDPE), providing the critical first step in the biological PE deconstruction process. The mechanism of PE-oxidase activity, though, is yet to be understood. In this project, we aim to express and purify enzymes across the entire enzyme class in which LDPE oxidases reside. Over 40 eukaryotic and prokaryotic enzymes, spanning 40 distinct phylogenetic clades in the enzyme class, will be purified, tested for enzymatic activity, and ultimately evaluated for oxidase activity on LDPE substrates. The data generated from this project will be used to develop sequence and structural design rules that dictate LDPE oxidase activity within the class. Moreover, these data will be used as a preliminary dataset to develop machine learning-engineered LDPE-oxidases. By delineating design rules for enzymatic LDPE oxidation, this project will lay the groundwork for efficient biological LDPE oxidation, and ultimately conversion into upcycled products.

Instruments